Question

A cell is used to send current to an external circuit. How does the voltage across its terminals compare with its e.m.f.?

• A. Terminal voltage $<$ e.m.f.
• B. Terminal voltage $>$ e.m.f.
• C. Terminal voltage $=$ e.m.f.
• D. Terminal voltage $=(e.m.f.{)}^2$

Answer 1

The correct option is A Terminal voltage $<$ e.m.f.

Terminal voltage is always lesser than the emf of the cell. It is because of the drop in potential difference due to the current passing through the internal resistance of the cell.They are related by the equation E=V+Ir, where, I is the current and r is internal resistance of the cell.